Manic Metric Monday: Scientists Rethink the Kilogram

Monday kicks off an urgent meeting between some of the greatest minds in science, a debate that could result in a rethinking of the most elemental scientific measurements. Will the kilogram ever be the same?

The researchers are gathering at the Royal Society in London to discuss adjusting the fundamental mass of the kilogram.

The kilogram is the only unit in the International System of Units (SI) whose measurement is based on a physical object. And anyone who’s ever stepped on a scale knows how unkind Father Time can be to a person’s weight.

Currently, the kilogram is based on the mass of a platinum-iridium bar stored in a vault in a Parisian suburb. Aside from sounding like it should be the target of a heist in the next crime thriller, scientists estimate the bar’s mass may have actually changed by 50 micrograms over the years, which they note is “the mass of a small grain of sand 0.4 mm in diameter.”

The best and the brightest in science will meet to work out a constant on which the kilogram can be based. They anticipate it will be tied to the value of the Planck constant, h, which reflects the size of the smallest particles of physical matter in quantum physics.

But don’t jump on the scale just yet – there’s no set date to officially recalibrate the kilo’s mass. (via Royal Society)